CA2191877A1

CA2191877A1 - Improved reaction nut

Info

Publication number: CA2191877A1
Application number: CA002191877A
Authority: CA
Inventors: David Campbell
Original assignee: Individual
Current assignee: Hedley Purvis Ltd
Priority date: 1994-06-07
Filing date: 1995-06-01
Publication date: 1995-12-14
Also published as: ZA954700B; ES2126898T3; IN189596B; AU2623195A; NO965181L; US5749691A; JPH10501048A; NO307009B1; DE69506249D1; GB9411313D0; EP0765441B1; DK0765441T3; EP0765441A1; DE69506249T2; BR9507933A; MY116634A; NO965181D0; AU681294B2; WO1995033931A1

Abstract

A reaction nut for location on a threaded bolt, particularly a bolt to be tensioned by a hydraulic tensioning device, comprises a plurality of internally-threaded segments (22) movable between an outermost inoperative position radially spaced from the bolt (2), and an operative position making threaded engagement with the bolt (2), the segments (22) having tapering surfaces thereon, a primary ring member (16) movable axially relative to the segments (22) and having a corresponding tapering surface (18) thereon, first resilient means (20) biasing the tapering surface (18) of the primary ring member (16) into engagement with the tapering surfaces on said segments (22), and cam means (26) actuation of which moves the primary ring member (16) from a rest position to an axially displaced position against the bias of the first resilient means (20) whereby the segments (22) are moved by associated second resilient means (24) between their operative and inoperative positions.

Description

~ wossl33s3l 2191~77 PCTIC;B9510126~

IMPP~O~ED REA~CTION ~T
TECHNICAL FIEL~
This invention relates to a reaction nut, and more particularly to such a n-ut that can be quickly faster.ed to and released from an associated bolt, a preferred application of the r.ut being in a hydra~lic bolt tensisr.ing device.
BAC~GROUND
A hydraulic bolt tensioning devlce is basically a hydraulic jack positioned over a r.ut and bolt assembly with the bolt extending centrally through tne jack.
~ydraulic pressure is appiied to the de~ice such that a load is applied to the bolt to stretch the bolt whereby the associated nut can be tightened down to maintain the joint on release of the hydraulic pressure.
Reaction nuts are conventionally screwed onto the bolt, usually above the tensioning devices, to enable the load to be applied to the bolt.
~ owever, the length of balt extending through and abo~e the tensioning device can Gften be quite significant, and the application of the reaction nur. to the bolt can be a time consuming and exhaustive exercise, especially if the bolts are c~ large diameter and/or fine thread. This creates particular problems n hazardous environments, such as sub-sea and nuclear, ~ where the time spent by an operator in potentially dangerous areas must be kept to a minimum.
~ arious proposals have bGeen made to enable ~VOgs~3393l 2 1 9 1 8 7 ~ PCTIG~95/012~ ~

relatlvely ~uic~ application cf thr reaction nut ~o the associated bolt US specification no ~83288 discloses a split nut having two halves '~YhiCh car ke located onto a bolt in ary axial position therealong, the underside cf the n~t comprising a conical surface wnich locates into a compiementary recess in a washer or other suitable component, the nut being maintained in threaded engagement wit:h the bolt ~y co-operatir)r between the corresponding conical surfaces of the nut and washer This cor,cept has been applied to hydraulic bolt ter.siorers, for example as disclosed in U~
specificatior no 2193549 which shows a split reaction r.ut having a cam surface for engagement by thle surface of a complementary recess in the piston of the tensioner US specification no. 4438901 and UK specification no 21~36~8 disclose bolt ten.sioring devices in which the reaction nut incorporates a hydraulicall~-operated collet comprising â plurality of segments which, when activated hydraulicallyT, are urged into engagement with the bolt This concept is well established in m,ost industries utilisirg pulling/gripping, de~ices such as rope pullers and the like.
The major disadvar.tages of these known split nuts are tha'; they require an external force initially to engage the split rut~segments, and the maintenance of this force to keep the nut in positior.. In the absence .. . . . . ~

~ W09s133931 219 1~ 7 7 PCIIGB95/0126~

of this exterra force, the split nut and the ter.sloning device would disengage, thus resulting in these devices being difficul~, if not impossible, to use in upside down or horizontal positions without operatcr intervention It must also he borr,e in mind that, in practice, tensicning devices are seldom used singuiarli~, and operator intervention on eacn of a multitude of tensiorir.g devices is clearly undesirabie ST~MARY GF THE I~r~7E~TIO~
It would be desirable ',o be able to provide a reaction nut, in particular for a hydraulic bolt tensioning device, which can be applied onto a bolt quickly and with minimal operator interver.tion According to the present invention there is provided a reaction nut for location on a threaded bolt, the nut comprising a plurality of internally-t;.readed segments movable betweer. an outermost inoperative position radially spaced from the bolt, and an operative position making threaded engagemens with the bolt, said segments having tapering surfaces thereon, and a primary ring member movable axially relative to the segments and havirg a corresponding taperirg surface thereon, characterised by first resilient means biasing the tapering surface of the primary rins member into engagement with the tapering surfaces on said segmerts, and cam means actuation of which moves the primary ring member frorr1 a rest position to an axially displaced position against the wo~ 3393l ~ ~ PC1'1G~39~1012~
21~ 1871 ~r bias of said first resilient means whereb~; the segments are moved by a.ssociated second resllient means betweer their operati~e ard iroperative positions In one embodiment of the invention, the second resilient mear.s bias the segments towards tneir inoperative positions, actuztion of the cam mears resulting ir. movement of the segments from their aperative positions to their inoperative positions enabling ready location of the nut on the associated bolt In an alternati-re embodiment of ~he ir.ventior, the second resilient means bias the segments towards their operative positions, actuation of the cam means resultins in movement of t~he segments from their inoperative posi,tions to t'heir operative positions whereby the r.ut is locked onto the bolt The cam mears ma~r comprise one or more control me~bers extending radially cf the segments and biased by third resilient means into outermost positions relative to the segments and the primary ring member, raàially inward movement of the or each control member against said third resilient means moving the primary rirg member from its rest positior. to its axially àisplaced positior.
Preferably tr.e or each control member includes a ~apering surface thereon engaging the primary rir.g member to effect said axial movement thereof The reaction nut may further comprise a peripheral WO95/33~31 21 g 18 ~ 7 PCTIGss5/01261 sleeve member surrounding the or each control member and having an inner surface engaging said control d member or members, said inner surface of the sleeve member having a cam profile whereby, on movement of the sleeve member relative to the or each control member, said control member cr members are moved radially inwardly to move the primary ring member from iss rest position to its axially displaced position.
Said movement of the sleeve member may be rotary cr axial.
In an alternative embodiment of the inventio1l, the reaction nut further comprises a secondary ring member coaxial ~ith the primary ring member, a transverse surface of said secondary ring member being provided with a cam profile adapted to co-operate with a transverse surface of the primary rirg member ir. such a manner that rotation of the secondary ring member relative to the primary ring member results in movement of the primary ring member from its rest position to its axially displaced position.
Conveniently actuation of the cam means is effected remotel~m sRIEF DESCRIPTIOh' OE THE D~WINGS
Figs. la, ~a, 3 and 4a are vertical sectlor,s through embcdiments of the invention with the portion of the reaction nut to the left in ar. operative position engaging the bolt, and the portion of the reaction nut to the right in an inoperative positior.

rl~
WO')~/3393l 21~18 ~ PCT/GB9510l~64 ! : ' disengaged from the bolt;
Figs. 1_, 2_ and 4_ are plan views, par~ly in transverse section, of the reaction nuts of Figs. la, f 2_ and 4~ respectively, and Fig. S shows a reaction nut according i.o the in~er.tion incorporated in a bol~ tensioning device.
DESCRIPTIO~IS OF TH'E PREFERRED E~BODIMENTS
Referring ~o Figs. la and lb, there is shown a threaded bolt 2 on which is mour.ted a reacticn nut according to the inven~iorl and indicated generall~ ar 4.
The nut 4 comprises an annular body membfer f~
having a top wall ~ closely surrounding the bolt ' and having a downwardly and outwardly tapering lower surface lO thereto. A substantially cylindr cal sidewall 2 depends from the top wall ~. An annular flange 14 projects radiall-y inwardly of the lower end of the sidewall 12.
Slidably mounted within the body member 6 is a primary riny member 16 having an upwardly and outwardly tapering upper surface 18 and urged upwardly within the bod~ mem~er 6 by resillent means in the form of a plurality of coil springs ~0 reacting between the flange 14 and the underside of the rins member 16.
The reaction nut f-rrther comprises an internally threaded collet consistir.g of four segments 22 surrounding the bolt 2 and having upper an~ lower tapered surfaces conforming and co-operating ~f'i~h the 21~1~77 WO9513393l PcTJGn9s/0l26 surfaces 13,18 respectively. Coil springs 24 are provided between adjacent segments 22 to bias said segments 22 into outermost. inoperative positions disengaged from the bolt 2.
The springs 20 are stronger than the sprir.gs 24, and the arrangement so far described is .such that the springs 2~ urge the ring member 16 upward'y within the body member 6 so that the tapered surface 18 thereon engages t,he lower surfaces cf the segments 22, and wllereby the upper surfaces of the segments 22 are urgea into positive engagement with the tapered surface lO of the body member 6.
Thus it will be appreciated that the segments 22 are urged radially inwardly into threaded engagement with the bolt 2 as seen in the left hand side of Fig. 1_.
A pair of diametrically opposed control members in the form of buttons 26 are mounted in correspor.dina apertures formed in the sidewall 12 of the body member 6 to project radially therefrom, the buttons 26 being urged by coil springs 28 to the outermost positior.s sh,own to the left in Fig. la.
The buttons 26 can be moved radially of the nut 4 against the bias of the springs 28 towards innermost positions shown to the right of Fig. la, each button 26 having an upwardly and inwardly tapering lower surface 30 thereto. The relative positions of the buttons 26 and the ring member 16 are such that, with the buttons WO 95f33931 21~18 7 ~ P~T1C~B9510126J

1, .
26 in their outermost positiors, and with the rlng member in i~s uppermost position - ie with the segments 22 closed and in threaded ergagemen~ witn rhe bolt 2 - the upper, innermost ends of the surfaces 28 on the buttons 26 lie adjacent the top rim of the rins member 15 as seen to the left of Fig la Thus it will be appreciated that, on radiallv lnward movement of the buttons 26 against the bias of the springs 28, the taperir.g surfaces 35 thereon engage the rim Gf the ring member 16 and move said ring member dohnwardly within t.he body member 6 against the bias of the springs 2Q
As the ring member 16 moves downwardly, the spacir,g between the surfaces l0,18 ir.creases whereby the springs 24 can urge the segments 22 outwardly and apart while maintaining cortact of the segments 22 with the s~rfaces lQ,l8 On completion cf inward movement of the buttors 26, the segments 22 are disengaged from the bolt 2 as seer. to the right of Fig la.
On release of the buttons 26, the springs 2Q, which are stronger than the combined springs 24 anA 28, urge the rir.g member 16 back to lts uppermost position and rhe segmen~s 22 back to their innermost positions, ~hereby iocking the reaction nut 4 to the boit 2 In crder to apply the reaction nut 4 to the bo;t 2, the buttons 26 are depressed to move the segments 22 to their radially outermost positions, and the rut is 2191~ ~ 7 PCT/GB95/11126-l moved axially- down the bolt 2 tc the deslred position.
Once over the bolt 2, the buttons 26 are reieased, and the nut 4 is effectivel~ locked on the bolt 2.
Although Fig. l illustrates an arrangement in which the outermost rest position of the buttons 26 is associated with the segments 22 making locking threaded engagement with the bolt 2, said rest position of the buttons may be associated with the open position of th.e segmen~s 22, radially inward movement of the buttons 26 closing the segments 22 about the bolt 2.
Movement of the buttons 26 may be achieved in a variety of different ways Referring to Figs. 2a and 2_, the reaction nut includes a circumferential sleeve 32 mounted on, to surround, the body member 6 and the buttons 26. The sleeve 32 is a rotatable relative to the body member 6 and includes, on its ir.ner surface, a pair of diametrically-opposed cams 34. The configuration of said internal surface of the sleeve 32 is such that, in the angular position shown ir. Fig. 2_, the buttons 26 are unimpeded and can prolect to their radially outermost positions. ~owever, or. rotation of the sleeve 32 through 90~, the cams 34 are brought into er.gagement with the buttons 26 to move said but~ons 26 radially inwardly to their innermost positions, with consequential movement of the rir.g member 16 and segments 22.
Fig. 3 shows a reaction nut 4 incorporating a control member which is axially movable relative to the ~09513393' 219~ 877 BCT/GB95/0126~

I o remainder of the nut, the control member including a cvlirldrical sieeve portior. 36 the nternal ~urface of tne end extert of which is dswnwardl,v ard outwardl~
tapered at 38. On downward movement of the csntrsl member from thY posltion shswn ts the left of Fig. 3 .o tnat sr.own to tne right of Fig. 3, the tapering surface 38 engages the buttons 26 to move ~hem radially inwardly t.o their innermost positions, again witr.
conses,uential movement of the ring member 16 and segmer.ts 22.
Fig. 4 illustrates a reaction nut in whicrl L.he cam mear.s comprise a rotatable annular ring 4~ reacting between the body member 6 and the ring member 16. More sarticularly, the end of the ring member 16 remo~e from the surface 18 is provided with a pair sf diametrically opposed, radially-outwardly projecting flanges 42 theresn sverl~irg the free end sf the bod~ member 6.
The ring 40 is located between the flanges 42 ar.d sr.e bsd~ member 5, the springs 2Q urging the flanges 42 nts abutment with a surface of the ring 40.
Said surface of the ring 40 is pro~ided wish a pair of diametrically-opposed, upstanding cam profiles 44 thereon ~o effect an increased thickress r.c the rins, 40 in the regions of said profiles 44.
As seen to the left of Fig. 43 and with other thLan the ir.creased-tr.ickness region of the ring 48 betweer.
the flanges 42 and the body member 6, the ring member i6 is ir. its fully extended position resulting n ,, _ _ _ _ _ _ _ _ , .... .

9~/33931 Z~ 7 ~ PCTIGs~ \I

gripping of the bolt 2 by the segments 22. On rotation of the ring 40 to bring the cam profiles 44 between the respective flanges 42 and the body member 6, the rins member 16 is retracted within the boay member 6 against the bias of the springs 20 to release the .segments 22 from the bolt 2.
Clearly movement of the ring member 16 between its extended and retracted positions may be achieved by cam means other than those described and illustrated, whether linearly or rotatably operated.
Fig. 5 illustrates a reaction nut substantially in accordance with that of Figs. 1_ and lk incorporated into a bolt tensioning device. The body member is extended to form the piston 46 of the device slidably mounted in the cylinder 48 through the wall of which the cam means, in this case the buttons 2~, extend.
Thus there is provided a reaction nut that is particularly suited to remote controi and which has distinct additional advantages over current products.
The nut is of relatively simple construction and is economical to manufacture, maintenance being easy and relatively quic~. to carry out.
The nut does not require any specific configuration of outer surface to co-operate with the associated joint face, but can be shaped to suit particular requirements without affecting the basic operation of the nut.
The nut is readily adaptable to different methods WO 95,'3393 i ~ 1 ~ 18 7 7 I'CTJGB95/1) 1261 Si ~
of operatior. by the addition thereto of various mecharical or power means. Thus the nut can be reacily incorporated into a variety of different bolt wor!~ina devices, ir particular remotely operated devices.
Tn its simplest form, power operation is not required and the nut can be actuated manually.
The nut is totally self contained, without ary additional components that could be lost or mislaid.
The operation of the nut is such th.at it can be applied very quickly ~o long bolts, short bolts, corroded bolts, damaged bolts without any loss in reliability.
Under ~anual operation, and whether the nut i9 incorporated in a bolt working tool or is used as an ;n~p~nrs~nt unit, subsequer.t operations are hands-free once the nut is applied to the bol~s. This improves safety as the operator can stand clear of the equipmert while the load is being applied, and reduces operator fatigue, especially in upside-down operatior.s where the operatcr would otherwise have to hold the weight of the equipment for a good proportion of the operatior..

Claims

13

1 A reaction nut for location on a threaded bolt, the nut comprising a plurality of internally-threaded segments (22) movable between an outermost inoperative position radially spaced from the bolt (2), and an operative position making threaded engagement with the bolt (2), said segments (22) having tapering surfaces thereon, and a primary ring member (16) movable axially relative to the segments (22) and having a corresponding tapering surface (18) thereon, characterised by first resilient means (20) biasing the tapering surface (18) of the primary ring member (16) into engagement with the tapering surfaces on said segments (22), and cam means (26) actuation of which moves the primary ring member (16) from a rest position to an axially displaced position against the bias of said first resilient means (20) whereby the segments (22) are moved by associated second resilient means (24) between their operative and inoperative positions

2. A reaction nut as claimed in claim 1 in which the second resilient means (24) bias the segments (22) towards their inoperative positions, actuation of the cam means (26) resulting in movement of the segments (22) from their operative positions to their inoperative positions enabling ready location of the nut (4) on the associated bolt (2).

3. A reaction nut as claimed in claim 1 in which the second resilient means (24) bias the segments (22) towards their operative positions, actuation of the cam means (26) resulting in movement of the segments (22) from their inoperative positions to their operative positions whereby the nut (4) is locked onto the bolt (2).

4. A reaction nut as claimed in any one of claims 1 to 3 in which the cam means comprise one or more control members (26) extending radially of the segments (22) and biased by third resilient means into outermost positions relative to the segments (22) and the primary ring member (16), radially inward movement of the or each control member (26) against said third resilient means (28) moving the primary ring member (16) from its rest position to its axially displaced position.

5. A reaction nut as claimed in claim 4 in which the or each control member (26) includes a tapering surface (30) thereon engaging the primary ring member (16) effect said axial movement thereof.

6. A reaction nut as claimed in claim 4 or claim 5 and further comprising a peripheral sleeve member (32) surrounding the or each control member (26) and having an inner surface engaging said control member or members (26), said inner surface of the sleeve member (32) having a cam profile (34) whereby, on movement of the sleeve member (32) relative to the or each control member (26), said control member or members (26) are moved radially inwardly to move the primary ring member (16) from its rest position to its axially displaced position.

7. A reaction nut as claimed in claim 6 in which movement of the sleeve member (32) is rotary.

8. A reaction nut as claimed in claim 6 in which movement of the sleeve member (32) is linear.

9. A reaction nut as claimed in claim 4 or claim 5 and further comprising a secondary ring member (40) coaxial with the primary ring member (16), a transverse surface of said secondary ring member (40) being provided with a cam profile (44) adapted to co-operate with a transverse surface of the primary ring member (16) results in movement of the primary ring member (16) from its rest position to its axially displaced position.

10. A reaction nut as claimed in any one of claims 1 to 9 in which the cam means (26) are actuated remotely.